iio: mma8452: Basic support for transient events.

The event is triggered when the highpass filtered absolute acceleration
exceeds the threshold.
Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/mma8452.c

@@ -9,7 +9,7 @@
  *
  * 7-bit I2C slave address 0x1c/0x1d (pin selectable)
  *
- * TODO: interrupt, thresholding, orientation / freefall events, autosleep
+ * TODO: orientation / freefall events, autosleep
  */
 
 #include <linux/module.h>
@@ -19,20 +19,33 @@
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/triggered_buffer.h>
+#include <linux/iio/events.h>
 #include <linux/delay.h>
 
 #define MMA8452_STATUS 0x00
 #define MMA8452_OUT_X 0x01 /* MSB first, 12-bit  */
 #define MMA8452_OUT_Y 0x03
 #define MMA8452_OUT_Z 0x05
+#define MMA8452_INT_SRC 0x0c
 #define MMA8452_WHO_AM_I 0x0d
 #define MMA8452_DATA_CFG 0x0e
+#define MMA8452_TRANSIENT_CFG 0x1d
+#define MMA8452_TRANSIENT_CFG_ELE		BIT(4)
+#define MMA8452_TRANSIENT_CFG_CHAN(chan)	BIT(chan + 1)
+#define MMA8452_TRANSIENT_SRC 0x1e
+#define MMA8452_TRANSIENT_SRC_XTRANSE		BIT(1)
+#define MMA8452_TRANSIENT_SRC_YTRANSE		BIT(3)
+#define MMA8452_TRANSIENT_SRC_ZTRANSE		BIT(5)
+#define MMA8452_TRANSIENT_THS 0x1f
+#define MMA8452_TRANSIENT_THS_MASK	0x7f
 #define MMA8452_OFF_X 0x2f
 #define MMA8452_OFF_Y 0x30
 #define MMA8452_OFF_Z 0x31
 #define MMA8452_CTRL_REG1 0x2a
 #define MMA8452_CTRL_REG2 0x2b
 #define MMA8452_CTRL_REG2_RST		BIT(6)
+#define MMA8452_CTRL_REG4 0x2d
+#define MMA8452_CTRL_REG5 0x2e
 
 #define MMA8452_MAX_REG 0x31
 
@@ -48,6 +61,8 @@
 #define MMA8452_DATA_CFG_FS_4G 1
 #define MMA8452_DATA_CFG_FS_8G 2
 
+#define MMA8452_INT_TRANS	BIT(5)
+
 #define MMA8452_DEVICE_ID 0x2a
 
 struct mma8452_data {
@@ -274,6 +289,126 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
 	}
 }
 
+static int mma8452_read_thresh(struct iio_dev *indio_dev,
+			       const struct iio_chan_spec *chan,
+			       enum iio_event_type type,
+			       enum iio_event_direction dir,
+			       enum iio_event_info info,
+			       int *val, int *val2)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_THS);
+	if (ret < 0)
+		return ret;
+
+	*val = ret & MMA8452_TRANSIENT_THS_MASK;
+
+	return IIO_VAL_INT;
+}
+
+static int mma8452_write_thresh(struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan,
+				enum iio_event_type type,
+				enum iio_event_direction dir,
+				enum iio_event_info info,
+				int val, int val2)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+
+	return mma8452_change_config(data, MMA8452_TRANSIENT_THS,
+				     val & MMA8452_TRANSIENT_THS_MASK);
+}
+
+static int mma8452_read_event_config(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_CFG);
+	if (ret < 0)
+		return ret;
+
+	return ret & MMA8452_TRANSIENT_CFG_CHAN(chan->scan_index) ? 1 : 0;
+}
+
+static int mma8452_write_event_config(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan,
+				      enum iio_event_type type,
+				      enum iio_event_direction dir,
+				      int state)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+	int val;
+
+	val = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_CFG);
+	if (val < 0)
+		return val;
+
+	if (state)
+		val |= MMA8452_TRANSIENT_CFG_CHAN(chan->scan_index);
+	else
+		val &= ~MMA8452_TRANSIENT_CFG_CHAN(chan->scan_index);
+
+	val |= MMA8452_TRANSIENT_CFG_ELE;
+
+	return mma8452_change_config(data, MMA8452_TRANSIENT_CFG, val);
+}
+
+static void mma8452_transient_interrupt(struct iio_dev *indio_dev)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+	s64 ts = iio_get_time_ns();
+	int src;
+
+	src = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_SRC);
+	if (src < 0)
+		return;
+
+	if (src & MMA8452_TRANSIENT_SRC_XTRANSE)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_X,
+						  IIO_EV_TYPE_THRESH,
+						  IIO_EV_DIR_RISING),
+			       ts);
+
+	if (src & MMA8452_TRANSIENT_SRC_YTRANSE)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Y,
+						  IIO_EV_TYPE_THRESH,
+						  IIO_EV_DIR_RISING),
+			       ts);
+
+	if (src & MMA8452_TRANSIENT_SRC_ZTRANSE)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Z,
+						  IIO_EV_TYPE_THRESH,
+						  IIO_EV_DIR_RISING),
+			       ts);
+}
+
+static irqreturn_t mma8452_interrupt(int irq, void *p)
+{
+	struct iio_dev *indio_dev = p;
+	struct mma8452_data *data = iio_priv(indio_dev);
+	int src;
+
+	src = i2c_smbus_read_byte_data(data->client, MMA8452_INT_SRC);
+	if (src < 0)
+		return IRQ_NONE;
+
+	if (src & MMA8452_INT_TRANS) {
+		mma8452_transient_interrupt(indio_dev);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
 static irqreturn_t mma8452_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
@@ -316,6 +451,31 @@ static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
 	return 0;
 }
 
+static const struct iio_event_spec mma8452_transient_event[] = {
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_RISING,
+		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
+		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE)
+	},
+};
+
+/*
+ * Threshold is configured in fixed 8G/127 steps regardless of
+ * currently selected scale for measurement.
+ */
+static IIO_CONST_ATTR_NAMED(accel_transient_scale, in_accel_scale, "0.617742");
+
+static struct attribute *mma8452_event_attributes[] = {
+	&iio_const_attr_accel_transient_scale.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group mma8452_event_attribute_group = {
+	.attrs = mma8452_event_attributes,
+	.name = "events",
+};
+
 #define MMA8452_CHANNEL(axis, idx) { \
 	.type = IIO_ACCEL, \
 	.modified = 1, \
@@ -332,6 +492,8 @@ static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
 		.shift = 4, \
 		.endianness = IIO_BE, \
 	}, \
+	.event_spec = mma8452_transient_event, \
+	.num_event_specs = ARRAY_SIZE(mma8452_transient_event), \
 }
 
 static const struct iio_chan_spec mma8452_channels[] = {
@@ -355,6 +517,11 @@ static const struct iio_info mma8452_info = {
 	.attrs = &mma8452_group,
 	.read_raw = &mma8452_read_raw,
 	.write_raw = &mma8452_write_raw,
+	.event_attrs = &mma8452_event_attribute_group,
+	.read_event_value = &mma8452_read_thresh,
+	.write_event_value = &mma8452_write_thresh,
+	.read_event_config = &mma8452_read_event_config,
+	.write_event_config = &mma8452_write_event_config,
 	.debugfs_reg_access = &mma8452_reg_access_dbg,
 	.driver_module = THIS_MODULE,
 };
@@ -425,6 +592,38 @@ static int mma8452_probe(struct i2c_client *client,
 	if (ret < 0)
 		return ret;
 
+	/*
+	 * By default set transient threshold to max to avoid events if
+	 * enabling without configuring threshold.
+	 */
+	ret = i2c_smbus_write_byte_data(client, MMA8452_TRANSIENT_THS,
+					MMA8452_TRANSIENT_THS_MASK);
+	if (ret < 0)
+		return ret;
+
+	if (client->irq) {
+		/*
+		 * Although we enable the transient interrupt source once and
+		 * for all here the transient event detection itself is not
+		 * enabled until userspace asks for it by
+		 * mma8452_write_event_config()
+		 */
+		int supported_interrupts = MMA8452_INT_TRANS;
+
+		/* Assume wired to INT1 pin */
+		ret = i2c_smbus_write_byte_data(client,
+						MMA8452_CTRL_REG5,
+						supported_interrupts);
+		if (ret < 0)
+			return ret;
+
+		ret = i2c_smbus_write_byte_data(client,
+						MMA8452_CTRL_REG4,
+						supported_interrupts);
+		if (ret < 0)
+			return ret;
+	}
+
 	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
 		(MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
 	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
@@ -437,9 +636,20 @@ static int mma8452_probe(struct i2c_client *client,
 	if (ret < 0)
 		return ret;
 
+	if (client->irq) {
+		ret = devm_request_threaded_irq(&client->dev,
+						client->irq,
+						NULL, mma8452_interrupt,
+						IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+						client->name, indio_dev);
+		if (ret)
+			goto buffer_cleanup;
+	}
+
 	ret = iio_device_register(indio_dev);
 	if (ret < 0)
 		goto buffer_cleanup;
+
 	return 0;
 
 buffer_cleanup: